CN110360548B - Low NOx combustor based on plasma excitation staged combustion enhancement - Google Patents

Abstract

The invention discloses a low NOx burner based on plasma excitation and staged combustion reinforcement, which comprises a primary air channel, a secondary air channel, an ionization channel, a coal powder shade impact block, a coal powder separator, a sliding arc combustion reinforcement stabilizer, a swirler, a high-voltage electrode, a grounding electrode and high-temperature-resistant insulating ceramics, wherein the coal powder shade separator and the coal powder separator are arranged in the primary air channel, the secondary air channel and the ionization channel are embedded outside the rear end of the primary air channel, the rear end of the secondary air channel consists of an inner ring ionization channel and an outer ring ionization channel to form an inner and outer double ring dielectric barrier discharge system, a detachable sliding arc combustion reinforcement stabilizer is arranged at the outlet of the primary air channel, the structure of the coal powder burner is optimized and improved by adopting a mode of combining dielectric barrier discharge excitation and sliding arc discharge, and active particles of secondary air are promoted by utilizing the chemical effect of non-equilibrium plasma, the purposes of plasma-assisted efficient combustion, stable and reliable combustion of a combustion stabilizer and the like are achieved.

Description

Low NOx burner based on plasma excitation staged intensified combustion

technical field

The invention relates to the technical field of pulverized coal burners, in particular to a low-NOx burner based on plasma excitation grading intensified combustion.

Background technique

The ignition and stable combustion of large-scale industrial pulverized coal boilers are traditionally achieved by burning rare fuels such as heavy oil or natural gas. . Therefore, boiler ignition and stable combustion oil are used as an important indicator to evaluate. In order to reduce the consumption of heavy oil (natural gas), the traditional method is to increase the fineness of pulverized coal and improve the air-powder mixture and secondary air. Preheating temperature, using pre-combustion chamber burners, using small oil guns for ignition, etc. However, these methods have come to an end. If you want to further reduce fuel oil and finally use no oil, you must adopt a completely new process that is completely different from the traditional one. The process should not only ensure the improvement of the economy of the combustion process, but also improve the ecological conditions of the thermal power plant.

The operation and technical maintenance cost of using plasma ignition is only 15% to 20% of the cost of using heavy oil for ignition. For newly built power plants, tens of millions of initial investment and trial operation costs can be saved; It can be invested in the initial stage of ignition, thus reducing the environmental pollution caused by the emission of a large amount of smoke and dust in the initial stage of ignition. In addition, after the power plant uses a single fuel, the transportation and storage of oil products are reduced, and the environment of the power plant is also improved. Plasma contains a large number of chemically active particles, such as atoms (C, H, O), atomic groups (OH, _H2 , _O2 ), ions ( _O2- , H2-, OH-, O-, H ₊ ) and electrons It can accelerate the thermochemical conversion and promote the complete combustion of the fuel; the power plant can run on a single fuel, which simplifies the system and simplifies the operation mode; canceling the fuel system in front of the furnace naturally avoids various accidents often caused by the fuel system.

Plasma excitation technology has great potential for application in pulverized coal burners due to its advantages of improving reaction activity, temperature rise effect, and disturbing flow field, which are beneficial to intensify combustion, promote stable and reliable combustion, and reduce NOx emissions. Therefore, the present invention is based on the plasma excitation staging enhanced combustion low NOx burner, which will greatly promote the application of the pulverized coal burner technology.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to provide a low-NOx burner based on plasma excitation staged and enhanced combustion, which can solve the above-mentioned problems in the prior art.

To this end, the present invention adopts the following technical solutions: including a primary air channel, a secondary air channel, an ionization channel, a pulverized coal concentration impact block, a pulverized coal separator, a sliding arc enhanced combustion stabilizer, a cyclone, a high-voltage electrode, Ground electrode, high temperature resistant insulating ceramics, wherein, coal dust impact block and coal dust separator are arranged in the primary air channel, and a secondary air channel is embedded on the outer side of the rear end of the primary air channel;

The front end of the secondary air channel is composed of an inner secondary swirl channel and an outer secondary swirl channel. The cyclone is used to generate a high-speed rotating turbulent flow field. The airflow velocity can maximize the cooling effect of the burner wall;

The rear end of the secondary air channel is composed of an ionization channel, and the ionization channel is composed of an inner ring ionization channel and an outer ring ionization channel, wherein the high-voltage electrode is embedded in the middle of high temperature resistant insulating ceramics, and is integrally fixed on the secondary air channel bracket, The burner wall and the outer wall of the secondary air passage are made of high temperature and corrosion resistant metal materials and serve as ground electrodes to form an inner and outer double-ring dielectric barrier discharge system;

A detachable sliding arc intensified combustion stabilizer is arranged at the outlet of the primary air passage, wherein the opposite annular high-voltage electrodes in the sliding arc intensified combustion and stabilizer are embedded on the high-temperature resistant insulating ceramic 2 and fixed on the sliding arc intensified combustion stabilizer. On the outer wall of the combustion stabilizer, the opposite annular ground electrode is directly fixed on the outer wall of the sliding arc intensified combustion stabilizer. During operation, a high-voltage power supply is applied to form a sliding arc discharge and generate a plasma discharge area. The sliding arc enhanced combustion stabilizer has two major functions. One is to achieve the purpose of assisting and intensified combustion due to the chemical effect of the plasma and the effect of temperature rise.

The beneficial effects of the present invention are: the low-NOx burner based on plasma excitation and staging intensified combustion provided by the present invention abandons the traditional boiler ignition and stable combustion mode of oil consumption, and has the following advantages: the use of dielectric barrier discharge excitation and The structure of the pulverized coal burner is optimized and improved by the combination of sliding arc discharge, the non-equilibrium plasma chemical effect is used to increase the active particles of the secondary air, and the reactivity in the furnace is enhanced, and the temperature rise effect and chemical effect of the sliding arc plasma are used. Strengthen the combustion intensity at the outlet of the primary air channel, use the structure of the burner to promote the stability of combustion, and finally achieve effective reduction of NOx emissions, plasma-assisted efficient combustion, and stable and reliable combustion of the burner on the basis of safe and economical operation of the boiler , anti-slagging, anti-ablation and other purposes. At the same time, this scheme can work normally as a common low NOx stage burner when no high voltage is applied.

Description of drawings

Fig. 1 is the overall structure diagram of the low-NOx burner of the present invention with plasma excitation and staged enhanced combustion;

Fig. 2 is a schematic diagram of a sliding arc enhanced combustion stabilizer according to the present invention.

Description of symbols in the figure: 1- primary air channel, 2- burner wall, 3- secondary air channel bracket, 4- inner secondary swirl channel, 5- outer secondary swirl channel, 6- secondary air channel outer wall , 7- high voltage electrode, 8- high temperature insulating ceramic 1, 9- inner ring ionization channel, 10- outer ring ionization channel, 11- pulverized coal concentration impact block, 12- pulverized coal separator, 13- sliding arc enhanced combustion stability Burner, 14-high temperature resistant insulating ceramic two, 15-opposed annular high voltage electrode, 16-opposed annular ground electrode, 17-plasma discharge area, cyclone 18, cyclone 19.

Detailed ways

In order to understand the above objects, features and advantages of the present invention more clearly, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

The following describes a low NOx burner based on plasma excitation staged enhanced combustion provided according to an embodiment of the present invention with reference to FIGS. 1-2 .

1 to 2, the present invention includes a primary air channel 1, a secondary air channel, an ionization channel, a pulverized coal concentration impact block 11, a pulverized coal separator 12, a sliding arc enhanced combustion stabilizer 13, and a cyclone , high-voltage electrode 7, grounding electrode, high temperature resistant insulating ceramics, among which, the coal powder concentration impact block 11 and the coal powder separator 12 are arranged in the primary air channel 1, and the secondary air channel is embedded outside the rear end of the primary air channel 1;

The front end of the secondary air channel is composed of an inner secondary swirl channel 4 and an outer secondary swirl channel 5. The cyclone 18 and the cyclone 19 are used to generate a high-speed rotating turbulent flow field. The horizontal front end of the secondary air channel is designed as The tapered orifice is used to enhance the airflow velocity to maximize the cooling effect of the burner wall;

The rear end of the secondary air channel is composed of an ionization channel. The ionization channel is composed of an inner ring ionization channel 9 and an outer ring ionization channel 10. The high voltage electrode 7 is embedded in the middle of the high temperature resistant insulating ceramic 18, and is integrally fixed to the secondary air channel bracket. 3, the burner wall 2 and the outer wall 6 of the secondary air passage are made of high-temperature and corrosion-resistant metal materials and serve as ground electrodes to form an inner and outer double-ring dielectric barrier discharge system;

A detachable sliding arc intensified combustion stabilizer 13 is arranged at the outlet of the primary air channel 1, wherein the opposite annular high-voltage electrodes 15 in the sliding arc intensified combustion stabilizer 13 are embedded on the high temperature resistant insulating ceramic 2 14 and fixed on the second. On the outer wall of the sliding arc intensified combustion stabilizer 13 , the opposite annular ground electrode 16 is directly fixed on the outer wall of the sliding arc intensified combustion and stabilizer 13 . During operation, a high voltage power supply is applied to form a sliding arc discharge and generate a plasma discharge area 17 . The sliding arc intensified combustion stabilizer 13 has two major functions, one is to achieve the purpose of assisting and intensified combustion due to the chemical effect and temperature rise effect of the plasma, and the other is to effectively control the combustion stability through the opposed double-ring structure.

The working principle of the present invention: the air powder enters the burner through the primary air channel 1, and the air and powder mixture after entering the burner will pass through the coal powder concentration and impact block 11, so that the air powder concentration and air flow velocity of the system are at a level that is very conducive to ignition. Therefore, a continuous and stable ignition is completed. During the combustion process, the dense-phase airflow enters the inside of the pulverized coal separator 12 , and the thin-phase airflow flows through the outside of the pulverized coal separator 12 . The air-powder mixture processed by the pulverized coal concentration impact block 11 will be mixed with the non-equilibrium plasma generated by the ionization of the high-voltage electrode 7, and the mixed mixture will be reprocessed by the pulverized coal separator 12, and finally contains a large amount of non-equilibrium plasma. The mixture of plasma active particles will be directly ignited by the sliding arc enhanced combustion stabilizer 13 . The dielectric barrier discharge working gas enters the inner ring ionization channel 9 and the outer ring ionization channel 10 from the outer secondary swirl channel 5. After being ionized by the high voltage electrode 7, a large amount of non-equilibrium plasma that can stimulate combustion will be generated, and the non-equilibrium plasma generated by the ionization will be generated. The equilibrium plasma will enter into the burner driven by the working gas in the inner secondary swirl channel 4 and the outer secondary swirl channel 5, and will stimulate the combustion process.

Claims (2)

1. A low NOx combustor based on plasma excitation staged combustion reinforcement is characterized by comprising a primary air channel (1), a secondary air channel, an ionization channel, a pulverized coal thick and thin impact block (11), a pulverized coal separator (12), a sliding arc combustion reinforcement combustion stabilizer (13), a cyclone, a high-voltage electrode (7), a grounding electrode and high-temperature-resistant insulating ceramics, wherein the pulverized coal thick and thin impact block (11) and the pulverized coal separator (12) are arranged in the primary air channel (1), and the secondary air channel is embedded in the outer side of the rear end of the primary air channel (1); a detachable sliding arc intensified combustion flame stabilizer (13) is arranged at the outlet of the primary air channel (1);

the secondary air channel front end comprises an inner secondary cyclone channel (4) and an outer secondary cyclone channel (5), the horizontal front end of the secondary air channel is a reducer, the secondary air channel rear end comprises an ionization channel, the ionization channel comprises an inner ring ionization channel (9) and an outer ring ionization channel (10), wherein a high-voltage electrode (7) is embedded in the middle of a high-temperature-resistant insulating ceramic I (8) and integrally fixed on a secondary air channel support (3), and a combustor wall (2) and a secondary air channel outer wall (6) are made of high-temperature-resistant and corrosion-resistant metal materials and serve as grounding electrodes to form an inner and outer double-ring dielectric barrier discharge system.

2. The low NOx burner based on the plasma excitation staged combustion enhancement is characterized in that an opposite annular high-voltage electrode (15) in the sliding arc enhanced combustion burner stabilizer (13) is embedded on a high-temperature resistant insulating ceramic II (14) and fixed on the outer wall of the sliding arc enhanced combustion burner stabilizer (13), an opposite annular grounding electrode (16) is directly fixed on the outer wall of the sliding arc enhanced combustion burner stabilizer (13), and a high-voltage power supply is applied to form a sliding arc discharge and generate a plasma discharge area (17) during operation.

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